I did as you instructed, imported a couple more photos, opened and closed LR, and still nothing in the new cache.

I checked the disk by opening PS, and it loads its scratch disk info onto the disk. So, the disk appears to be working fine.

You don't say what you did after opening LR; did you go into Develop and do some editing? The ACR Cache is where preview data for the Develop module is stored, which is separate and different from Library previews, so unless you have taken an image into Develop, nothing will be written to the cache.

If it is not writing Develop previews to the location designated in Preferences, I would expect that it is creating them somewhere else. The question is where. The default location is "C:\Users\user\AppData\Local\Adobe\CameraRaw\"; I wonder if it is writing there despite the Preferences entry.

Another possibility occurs to me: Are you converting to the new DNGs with fast load previews incorporated in them. In that case there would be no need for cached previews so LR may not bother creating them.

If it is not writing Develop previews to the location designated in Preferences, I would expect that it is creating them somewhere else. The question is where. The default location is "C:\Users\user\AppData\Local\Adobe\CameraRaw\"; I wonder if it is writing there despite the Preferences entry.

Another possibility occurs to me: Are you converting to the new DNGs with fast load previews incorporated in them. In that case there would be no need for cached previews so LR may not bother creating them.

I do have 12.8 MB in four folders in the default location. I cleared the cache yesterday, but didn't check to see if that imediately decreased the default cache size.

My file are all tiffs from film scans, with a few jpegs from a p&s camera. No DNGs.

My file are all tiffs from film scans, with a few jpegs from a p&s camera. No DNGs.

That's probably the reason that you don't have anything in your ACR Cache. I believe that what the ACR Cache stores is some of the base level demosaicing data from RAW files. This is for speeding up the develop module, which needs to read data from the RAW file, demosaic it and render the image each time. This is different than rendering 1:1 previews, those are used in the Loupe view but not in the Develop module.

If you don't have any RAW files, there's nothing to store in the ACR cache

Thanks, Sheldon. I should have mentioned in my initial post that I don't work with RAW images. It didn't occur to me that my file types would be an important consideration for my cache question. Sorry for the oversight.

Another possibility occurs to me: Are you converting to the new DNGs with fast load previews incorporated in them. In that case there would be no need for cached previews so LR may not bother creating them.

Exactly what I'm not seeing after converting to the new option. I'm thrilled to no longer have an ACR cache to deal with.